China on Wednesday slammed Japan for its "reckless and irresponsible" move to push forward a plan to release nuclear-contaminated water from the Fukushima Daiichi nuclear power plant into the sea, urging Tokyo to fully consult with stakeholders and relevant international institutions.

In response to the International Atomic Energy Agency's third report on Fukushima water treatment published on Dec 29, Foreign Ministry spokeswoman Mao Ning said at a regular news conference that the ocean discharge plan for the contaminated water is "by no means" Japan's domestic affair.

But as the work of the IAEA's technical working group is still underway and no conclusion has been reached, Mao described Japan's moves to push ahead with discharge preparations as "reckless and irresponsible".

"China once again urges Japan to pay attention to the legitimate and justifiable concerns of the international community and fully consult with stakeholders, including its neighboring countries and Pacific Island countries, as well as relevant international institutions," Mao said.

Japan should adopt an open, transparent, science-based and safe approach in disposing the water, and accept strict supervision by the IAEA, she added.

Mao said the report focuses on the disposal of nuclear-contaminated water and its environmental impact, and proposes methods and plans for the assessment and review of relevant data.

She noted that no conclusion has been reached yet on issues of great concern by all parties, such as the authenticity and accuracy of data and whether the data collection methods meet safety standards.

The IAEA report has once again demonstrated that the international community's concerns over the accuracy of data on nuclear-contaminated water, the efficacy of the treatment system and the uncertainty of environmental impact are well-founded, Mao added.

In July, Japan's Nuclear Regulation Authority officially approved Tokyo Electric Power Company's discharge plan, which will be implemented from spring 2023.The endorsement provoked concerns from local fishermen and objections from Asian neighbors.

The IAEA Task Force's review mission visited Japan in February and March last year and released relevant reports without any conclusive opinions.